Effect of mild hyponatremia on in-hospital falls of elderly hospitalized patients: A retrospective, cohort study

This study investigated the association between hyponatremia and falls in elderly hospitalized patients, focusing on mild hyponatremia as a potential risk factor. A retrospective analysis of 16,952 patients admitted to Kochi Medical School Hospital from 2012 to 2021 was performed. Serum sodium levels were categorized, and falls during a 30-day observation period were recorded. A Cox proportional hazards model and a machine learning model were used to estimate risk and explore interactions. Mild hyponatremia (130–134 mEq/L) was identified as an independent risk factor for falls (hazard ratio: 1.42, 95 % confidence interval 1.16–1.74), especially in patients with higher activities of daily living. The fall prediction model showed an area under the curve (AUC) of 0.780 (95 % confidence interval 0.751–0.806). A significant association between mild hyponatremia and falls in elderly hospitalized patients was found. The findings highlight the need for targeted fall prevention and further research into the underlying mechanisms. Mild hyponatremia may serve as a clinical marker for fall risk, especially in patients with independent activities of daily living.